1. Field of the Invention
The invention relates to a wiper device provided in a vehicle, such as an automobile or a truck.
2. Description of the Related Art
Generally, such a wiper device is adapted to wipe a windshield surface of a vehicle by the reciprocating movement of a blade, which is caused by a driving operation of a wiper drive unit. Hitherto, a device, in which each of blades 13 swings in an arc, as illustrated in FIGS. 7(A) and 7(B), has been known as a type conventional wiper device.
Meanwhile, in recent years, windshields of various shapes have been provided in vehicles to improve the design and visibility thereof. For example, in the case where a rectangular windshield is used, the conventional wiper device, in which each of the blades 13 is adapted to simply swing in an arc, has encountered a problem in that there are many regions B, as shown in FIGS. 7(A) and 7(B), which have been left unwiped, on the windshield surface.
Thus, there has been proposed another wiper device, configured so that the parallel displacement of blades is achieved by using two sets of parallel links and a gear mechanism interposed therebetween, as disclosed in the Japanese Unexamined Patent Publication No. 4-173452. Using such a wiper device, nearly the entire rectangular windshield surface can be wiped.
This latter wiper device, however, requires the gear mechanism and thus has problems in that the number of components is large and that the configuration is complex. Further, such a wiper device has another problem in that the aforementioned two sets of parallel links are provided in such a way as to cover the windshield surface so they obstruct a driver's view not only when the blades perform the wiping operation, but also when the blades are not performing the wiping operation. It is, thus, difficult to employ such a wiper device for a vehicle. The invention is created to solve the problems of the described wiper devices.